6,709 research outputs found
Single-stage, low-noise, advanced technology fan. Volume 4: Fan aerodynamics. Section 1: Results and analysis
Test results at design speed show fan total pressure ratio, weight flow, and adiabatic efficiency to be 2.2, 2.9, and 1.8% lower than design goal values. The hybrid acoustic inlet (which utilizes a high throat Mach number and acoustic wall treatment for noise suppression) demonstrated total pressure recoveries of 98.9% and 98.2% at takeoff and approach. Exhaust duct pressure losses differed between the hardwall duct and treated duct with splitter by about 0.6% to 2.0% in terms of fan exit average total pressure (depending on operating condition). When the measured results were used to estimate pressure losses, a cruise sfc penalty of 0.68%, due to the acoustically treated duct, was projected
Spatial Corrections of ROSAT HRI Observations
X-ray observations with the ROSAT High Resolution Imager (HRI) often have
spatial smearing on the order of 10 arcsec (Morse 1994). This degradation of
the intrinsic resolution of the instrument (5 arcsec) can be attributed to
errors in the aspect solution associated with the wobble of the space craft or
with the reacquisition of the guide stars. We have developed a set of IRAF/PROS
and MIDAS/EXSAS routines to minimize these effects. Our procedure attempts to
isolate aspect errors that are repeated through each cycle of the wobble. The
method assigns a 'wobble phase' to each event based on the 402 second period of
the ROSAT wobble. The observation is grouped into a number of phase bins and a
centroid is calculated for each sub-image. The corrected HRI event list is
reconstructed by adding the sub-images which have been shifted to a common
source position. This method has shown approx. 30% reduction of the full width
half maximum (FWHM) of an X-ray observation of the radio galaxy 3C 120.
Additional examples are presented.Comment: AandA latex (6 pages with 7 embedded postscript figures). Scheduled
for publication in the 1 Dec issue of Astron. Astrophys. Suppl. Serie
The Effects of Negative Legacies on the Adjustment of Parentally Bereaved Children and Adolescents
This is a report of a qualitative analysis of a sample of bereaved families in which one parent died and in which children scored in the clinical range on the Child Behavior Check List. The purpose of this analysis was to learn more about the lives of these children. They were considered to be at risk of developing emotional and behavioral problems associated with the death. We discovered that many of these âhigh riskâ children had a continuing bond with the deceased that was primarily negative and troubling for them in contrast to a comparison group of children not at risk from the same study. Five types of legacies, not mutually exclusive, were identified: health related, role related, personal qualities, legacy of blame, and an emotional legacy. Coping behavior on the part of the surviving parent seemed to make a difference in whether or not a legacy was experienced as negative
Temporal Feedback for Tweet Search with Non-Parametric Density Estimation
This paper investigates the temporal cluster hypothesis: in search tasks where time plays an important role, do relevant documents tend to cluster together in time? We explore this question in the context of tweet search and temporal feedback: starting with an initial set of results from a baseline retrieval model, we estimate the temporal density of relevant documents, which is then used for result reranking. Our contributions lie in a method to characterize this temporal density function using kernel density estimation, with and without human relevance judgments, and an approach to integrating this information into a standard retrieval model. Experiments on TREC datasets confirm that our temporal feedback formulation improves search effectiveness, thus providing support for our hypothesis. Our approach outperforms both a standard baseline and previous temporal retrieval models. Temporal feedback improves over standard lexical feedback (with and without human judgments), illustrating that temporal relevance signals exist independently of document content
The Elliptic curves in gauge theory, string theory, and cohomology
Elliptic curves play a natural and important role in elliptic cohomology. In
earlier work with I. Kriz, thes elliptic curves were interpreted physically in
two ways: as corresponding to the intersection of M2 and M5 in the context of
(the reduction of M-theory to) type IIA and as the elliptic fiber leading to
F-theory for type IIB. In this paper we elaborate on the physical setting for
various generalized cohomology theories, including elliptic cohomology, and we
note that the above two seemingly unrelated descriptions can be unified using
Sen's picture of the orientifold limit of F-theory compactification on K3,
which unifies the Seiberg-Witten curve with the F-theory curve, and through
which we naturally explain the constancy of the modulus that emerges from
elliptic cohomology. This also clarifies the orbifolding performed in the
previous work and justifies the appearance of the w_4 condition in the elliptic
refinement of the mod 2 part of the partition function. We comment on the
cohomology theory needed for the case when the modular parameter varies in the
base of the elliptic fibration.Comment: 23 pages, typos corrected, minor clarification
Using non-participant observation to uncover mechanisms: insights from a realist evaluation
This article outlines how a realist evaluation of dementia care in hospitals used non-participant observation to support the refinement and testing of mechanisms likely to lead to the use of person-centred care. We found that comments and explanations of their actions from hospital staff during observation periods provided insights into the reasoning that generated their actions for care in real time. This informed subsequent data collection and analysis. Two worked examples of mechanisms first identified during non-participant observation demonstrate (1) how they were uncovered, and (2) how this informed research activities for theory refinement. Early, iterative engagement with the analytic process, primarily involving reflection and debate with the research team, maximised the potential of observation data to support surfacing underlying mechanisms, linking them to specific contexts and outcomes.Peer reviewedFinal Accepted Versio
Shimura curve computations via K3 surfaces of Neron-Severi rank at least 19
It is known that K3 surfaces S whose Picard number rho (= rank of the
Neron-Severi group of S) is at least 19 are parametrized by modular curves X,
and these modular curves X include various Shimura modular curves associated
with congruence subgroups of quaternion algebras over Q. In a family of such K3
surfaces, a surface has rho=20 if and only if it corresponds to a CM point on
X. We use this to compute equations for Shimura curves, natural maps between
them, and CM coordinates well beyond what could be done by working with the
curves directly as we did in ``Shimura Curve Computations'' (1998) =
Comment: 16 pages (1 figure drawn with the LaTeX picture environment); To
appear in the proceedings of ANTS-VIII, Banff, May 200
Older consumersâ perceptions of functional foods and non-edible health-enhancing innovations
Increasing interest in health and well-being is likely to drive a growth in demand for products that have positive effects on health. Consumersâ acceptance of and willingness to buy functional foods has been widely studied, but there has not been research on consumersâ attitudes towards innovative non-edible products with health effects. This study examines how older consumers perceive functional foods and novel non-edible health-enhancing products, how willing they are to purchase such products, and how health orientation influences their views. As an example of a âradicalâ innovation, consumersâ acceptance of rubbing their hands in a specific soil-based mixture to modulate the immune system is explored. The research material, 13 thematic interviews, was collected in Lahti region, Finland, in 2015. The study indicates that the older consumersâ market is not homogeneous. Based on a qualitative, in-depth approach, the study distinguishes four consumer segments with different lay understandings of health and attitudes towards health-enhancing products, which influence people's willingness to purchase such products. The segments are health-seeking consumers, cautious consumers, critical consumers and natural health consumers. Various motives and barriers for using products with health claims are also identified. The case of rubbing hands in organic soil-based mixture indicates the difficulty of predicting which consumer segment will first adopt this kind of âradicalâ innovation. The results highlight that the credence qualities of a novel product must be communicated and advertised before entering the market while also taking into account the sensory properties of the product. âRadical innovationsâ must be in a form that consumers can easily accept.Peer reviewe
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